Costa Rica  sits astride a jagged series of volcanoes and mountains, part of the great Andean–Sierra Madre chain that runs the length of the western littoral of the Americas. The mountains rise in the nation’s northwestern corner as a low, narrow band of hills. They grow steeper and broader and ever more rugged until they gird Costa Rica coast to coast at the Panamanian border, where they separate the Caribbean and Pacific from one another as surely as if these were the Himalayas.
Volcanic activity has fractured this mountainous backbone into distinct cordilleras. In the northwest, the Cordillera de Guanacaste rises in a leap-frogging series of volcanoes, including Rincón de la Vieja  and Miravalles , whose steaming vents have been harnessed to provide geothermal energy. To the southeast is the Cordillera de Tilarán, dominated by Arenal , one of the world’s most active volcanoes. To the east is the Cordillera Central, with four great volcanoes—Poás , Barva , Irazú , and Turrialba —within whose cusp lies the Meseta Central, an elevated plateau ranging in height from 900 to 1,787 meters. To the south of the valley rises the Cordillera Talamanca, an uplifted mountain region that tops out at the summit of Cerro Chirripó (3,819 m), Costa Rica’s highest peak.
The Meseta Central , (central tableland, but really it’s a valley), the heart of the nation, comprises a rich agricultural valley cradled by the flanks of the Cordillera Talamanca to the south, and by the fickle volcanoes of the Cordillera Central to the north and east. San José , the capital, lies at its center. At an elevation of 1,150 meters, San José enjoys a springlike climate year-round.
The Meseta Central measures about 40 kilometers north to south and 80 kilometers east to west and is divided from a smaller valley by the low-lying Cerros de la Carpintera that rise a few miles east of San José. Beyond lies the somewhat smaller Cartago Valley, at a slightly higher elevation. To the east the turbulent Reventazón—a favorite of white-water enthusiasts—tumbles to the Caribbean  lowlands. The Río Virilla exits more leisurely, draining the San José Valley to the west.
The broad, wedge-shaped northern lowlands are cut off from the more densely populated Meseta Central by the Cordillera Central. The plains or llanuras extend along the entire length of the Río San Juan, whose course demarcates the Nicaraguan border. Farther south the plains narrow to a funnel along the Caribbean coast, framed by the steep eastern slopes of the central mountains, which run along a northwest–southeast axis. Numerous rivers drop quickly from the mountains to the plains. Beautiful beaches line the Caribbean coast, which sidles gently south.
Beaches are a major calling card of Costa Rica’s Pacific coast, which is deeply indented by two large gulfs—the Golfo de Nicoya (in the north) and Golfo Dulce  (in the south), enfolded by the hilly, hook-nosed peninsulas of Nicoya  and Osa , respectively. Mountains tilt precipitously toward the Pacific, and the slender coastal plain is only a few kilometers wide. North of the Golfo de Nicoya, the coastal strip widens to form a broad lowland belt of savanna—the Tempisque Basin. The basin is drained by the Río Tempisque and narrows northward until hemmed in near the Nicaraguan border by the juncture of the Cordillera de Guanacaste and rolling, often steep, coastal hills that follow the arc of the Nicoya Peninsula .
A narrow, 64-kilometer-long intermontane basin known as the Valle de El General  nestles comfortably between the Cordillera Talamanca and the coastal mountains—Fila Costeña—of the Pacific southwest.